Daemons of the Liberator: The Ritual Call of the Ferryman
Eternal Charon, strong to save,
Whose paddle calms the warping wave,
Whose arm protects with every sweep,
Your own appointed watch you keep;
Your mark of office, with silver gleams,
Keep safe us sailors, in the realm of dreams.
Keep us away from mystic shoals,
And shield from ghasts, our fragile souls,
No guardian, ever more steadfast,
We beg, this journey be not our last;
Your mark of office, with silver gleams,
Keep safe us sailors, in the realm of dreams.
So then once more we cross the veil,
To travel on the warping trail,
We beg, oh Charon, use your might,
That with it all our foes you smite;
Oh, let us see but writhing foam,
And bring us ever safely home.
Inspiration hit me after rewatching the Seapower Trailer.
Ferrymen are very powerful daemons, but they can not be everywhere at once. The Ritual Call of the Ferryman is used by the ship's Void Speaker, the Inanis Navis Oratore, to call upon a Ferryman to protect the ship on its journey before entering the warp. This could very much so evolve into ship-wide prayer.
Also yes, the Inanis Navis Oratore is the closest thing to a navigator that the Protectorate has, just that the person can be a regular psyker who is trained to communicate with the Ferrymen and help them keep the ship and crew safe. They get a lot of support tools to make this as risk free as possible, be it in the form of a psychic hood, a special communion chamber, etc...